1. Field of the Invention
This invention relates to the field of apparatus for reducing nitrogen oxide emission from internal combustion engines and turbines or hydrogen generation in general, and more particularly injector mixture device for receiving separate air/fuel mixtures within a combustion chamber and to which water may be added to the combusted effluent to increase the production of hydrogen.
2. Brief Description of the Prior Art
Normal burners operate air rich with fuel in a combustion chamber and react in roughly two stages. The first stage includes regions with air/fuel ratios near stoichiometric wherein high temperatures occur that induce initializing chemical reaction with fuels. Such temperatures result in high concentrations of nitrogen oxide NO.sub.x. The second stage operates air rich to achieve final overall air/fuel ratio. Its temperature is lower but often not sufficiently low that NO.sub.x cannot form, and this stage generally does not remove NO.sub.x formed in the first stage. The overall result is that NO.sub.x formed in both stages appears in the burner exhaust.
In co-pending U.S. patent application Nos. 08-148,472 and 07-997,450, technology was disclosed for attaining chemical equilibria between air and a large excess of fuel in an underoxidized burner through a process whereby the air-fuel mixture undergoes certain rapid flow reversals. The technology results in equilibration at a reasonably high temperature without resulting in formation of NO.sub.x, since its excessive fuel concentration preferentially causes reaction between air and fuel instead of N.sub.2.
It has been found that the technology of the copending patents results in products that are easily combusted with further air. As a consequence, a combustor with excess air for powering engines or for heating boilers, etc. which produces virtually zero NO.sub.x can be achieved by a related two stage process. The first stage comprises a fuel-rich burner of the type taught in the co-pending patents. The second stage uses similar technology but operates air rich. Products from the first stage and the excess air needed to attain the final air-fuel mixture are introduced into the second stage. In this stage, a mixture of the latter air and latter products undergo the same rapid flow reversals taught by the technology of the co-pending patents, which results in their rapid chemical equilibration. In view of the improved intrinsic reactivity of the fuel products obtained from the underoxidized burner, the induced flow reversals, and the relatively high concentration of hydrogen, equilibration can be induced in the second stage at higher ratio of air/fuel than normally used. This results in very low temperatures where NO.sub.x formation is very low. At higher air/fuel ratios where temperatures are higher, the technology also results in relatively low NO.sub.x because the air and fuel are very rapidly mixed so very high temperatures are largely avoided.
To attain needed conditions in the second stage, its injection is modified from those of the previous patents. This modification is necessary because the temperature of the underoxidized burner products can cause preignition therein whose effects are to lower the overall tendency to equilibrate and produce internal temperatures that are high enough to harm the injector. The change isolates the new air and first stage products from each other while within confined spaces of the injector.
Therefore, a long-standing need has existed to provide a novel injector for combining air/fuel into a volatile mixture which after combustion, may have water introduced thereto in order to produce additional hydrogen. Such a means of injection should be simple to manufacture and install into a combustion chamber of a NO.sub.x burner and preferably, the effluent at the exhaust nozzle may receive water injection.